I've got a Logitech K520 wireless keyboard, and sometimes I notice that a keypress has not been registered although I'm certain I hit the correct key. After a small experiment, I see the behavior can be reproduced by holding down the SHIFT key and pressing the I and N keys at the same time. The same if holding down the SHIFT key and pressing the V and B keys at the same time.
I suppose this has something to do with how the key switches are read by the keyboard controller. But I've not been able to reproduce the problem on the keyboard of the laptop that the Logitech keyboard is connected to.
Is this due to hardware design in the Logitech keyboard, or is something else going on?
43 Answers
This is due to the hardware. The Logitech K520 is a 2-Key Rollover (2KRO) keyboard. A 2KRO keyboard will be capable of registering at minimum 2 keys at the same time, but also some 3 key combinations, otherwise Ctrl + Alt + Del wouldn't work, but certain combinations will be limited to 2 simultaneous keypresses.
I have found these key combinations do not work with the Logitech K520
SHIFT + I + N
SHIFT + D + N
SHIFT + H + N
SHIFT + * + N
SHIFT + ~ + N
SHIFT + ~ + W
SHIFT + C + W
Most of those key combinations don't matter that much, but when typing: "SELECT DISTINCT" or "SELECT INTO" at speed it is very likely that you will press SHIFT + I + N at the same time as you usually press the 3rd key before you have had time to release the 2nd key when typing fast.
What is rollover?
Rollover is simply how well your keyboard can correctly register multiple keys being pressed simultaneously.
Not all keyboards are created equal when it comes to rollover. Where one keyboard might be able to handle half a dozen or more inputs, others might struggle to correctly recognise three keys pressed simultaneously.
Rollover is quantified as n-key rollover, where n is the minimum number of keys that can be correctly registered when pressed simultaneously. This is often written in its short form KRO. For example, 2–key rollover becomes 2KRO.
Many inexpensive keyboards have only 2KRO, while higher-end keyboards (and many mechanical keyboards) have 6KRO or higher. If a keyboard can register all of its keys being pressed simultaneously, then this is called NKRO.
Source
Try to press the keys that do not work in different spots, like on the edge or corner. This is a fairly common problem with these keyboards for some reason. My d key does it on mine. It simply will not work if pressed normally and I have to press it in the bottom right corner, in which case it works every time. It is a huge pain for games because of the whole wasd thing.
I had sa same problem with the "D" , I just have put a little bit of 3m tape (like 6 layers ) , seems like the key was a bit to short to mange o push the rubbers underneth.
right now works like a charm :D
